Enhanced Piezoelectric Performance of Composite Fibers Based on Lead-Free BCTZ Ceramics and P(VDF-TrFE) Piezopolymer for Self-Powered Wearable Sensors

Abstract

Flexible piezoelectric energy harvesters (f-PEHs) have recently become popular alternative power sources for smart and wearable devices. For applications in self-powered wearable devices and biomedical applications, f-PEHs should exhibit high flexibility, nontoxicity, and excellent piezoelectricity. In this study, we developed high-efficiency ultra-f-PEHs based on electrospun piezoelectric composite fiber (PCF) membranes composed of lead-free (Ba0.85Ca0.15)(Ti0.90Zr0.10)O3 (BCTZ) nanoparticles (NPs) and poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) fibers. In particular, post-treatments, including post-crystallization and an extra-poling process, were exploited to further enhance the piezoelectricity of the PCFs. The PCF membrane reached an output voltage of 36.5 V, a current signal of 1.09 μA, and an effective output power of 13.2 μW, which are higher compared to the previously reported PCF-based energy harvesters. Furthermore, an ultra-f-PEH consisting of aluminum electrodes, PCF membranes, and polydimethylsiloxane elastomers was proposed and successfully monitored tiny bio-signals, such as carotid pulses, vocalization, and articular bending motions. This study provides suggestions for applications in wearable and biomedical self-powered electronics using piezoelectric energy-harvesting systems.

A Self-Powered Piezoelectric Nanofibrous Membrane as Wearable Tactile Sensor for Human Body Motion Monitoring and Recognition

“…Despite the crucial roles electrospun nanofibers (ESNFs) have played in fields such as filtration and biomedical scaffolds [30][31][32][33], and been employed as substrates in a wide range of applications due to their unique porous structure, air permeability, and large surface to volume ratio [34,35], the ease of feature modification and attributes design greatly enhances the practicality of employing ESNF membranes as active functional layers for tactile sensing. For instance, incorporating additives such as ZnO nanorods into PVDF ESNFs can boost the power output [36]; introducing unique hierarchical structures such as core-sheath microfibers can bolster their flexibility to withstand intense external deformation [37]; utilizing post-treatment methods including crystallization and poling of fiber membranes can augment their piezoelectric properties [38]. Moreover, the fiber morphology can be tuned by varying parameter combinations, such as solution parameters including viscosity, surface tension, and process variables such as voltage, flow rate, collecting distance, rotating speed of the collector drum, as well as ambient parameters such as humidity and temperature [19,39,40].…”

Patchable Transparent Standalone Piezoelectric P(VDF-TrFE) Film for Radial Artery Pulse Detection

“…In spite of its various advantages, employment of P(VDF-TrFE) has been limited because its piezoelectric output response is relatively lower than that of its inorganic counterparts such as PZT. Fiber/textile based on P(VDF-TrFE) or its composites has been introduced, but production of fiber/textile is time and resource consuming with further requirement for complex manufacturing processes and special equipment [29][30][31][32]. Despite a continuous high demand for the piezoelectric biosensors, it has still been challenging to realize the piezoelectric biosensors based on biosafe materials without involving the complex structures.…”